1. Field of the Invention
The present invention relates to a production control system, and, more particularly, to a method of controlling parts processing stages and a system for controlling part processing stages.
2. Description of the Related Art
Conventionally, workers who carry out parts processing operations keep a record of processed parts in parts processing stages, and find the total number of the processed parts from the record at the end of each working day.
Japanese Laid-Open Patent Application No. 2000-322119 discloses a production system for conducting production control based on lot numbers. In this system, the start and the completion of each process are registered with each lot, so that progress in production of each lot can be monitored.
In the conventional method of finding the total number of processed parts at the end of each working day, however, real-time progress in processing cannot be monitored. As a result, there might be a delay in discovering an error or failure, such as production of defective parts through the processing stages, or hang-up or suspension of the processing machines and facility. If there is a delay in discovering an error or failure, it is difficult to find out in which stage the error or failure has occurred. Furthermore, by the conventional method of finding the total number of processed parts at the end of each working day, real-time process in processing operations cannot be monitored.
Japanese Laid-Open Patent Application No. 2000-322119 does not specify what a lot unit is made of, and does not either disclose a specific mechanism for monitoring real-time progress in processing.